Boost tourism by displaying your cities landmarks and attractions. Engage the public in planning. From zoning to historical preservation to redevelopment, your group can benefit from detailed public 3D building data. Foster economic development by integrating the 3D map into new business recruitment, site location planning, and real estate development. Emergency Services, risk mitigation, disaster planning, disaster response, etc.

I think the possibilities are nearly endless, the imagination and advances in technology will continue to answer this question for us as time goes on. While 3D is certainly not a replacement for the good ole fashion 2D maps, it is a great advance in our mapping capabilities and a great leap forward IMO. I think one of the greatest challenges would be to keep these data up-to-date. So we have added another dimension x, y & now z. Lets add t the time dimension too. ESRI has already started on this with time enabled data, so I'm sure it's already being done with 3D mapping too. Like Uncle Ben said, "with great power comes great responsibility" and maintaining the accuracy of 3D data may be a bigger challenge than with 2D.

I wonder what other advances in technology might hinder possible benefits of 3D mapping applications. For example, drones could certainly help with 3D mapping, but could they also limit some of the advantages of 3D mapping? Clouding the skies with moving features in the visible z dimension?

If you have a couple minutes you may find it interesting, it shows a third party app that is a lot like google street view, only it is within ArcMap. I would like to have that extension... There must be significant data collection involved in this process, similar to ortho imagery and oblique imagery, it's only a snapshot in time and as time passes it loses it's accuracy and value for showing the current.

At my previous place of employment with an civil engineering consultancy we used 3D mapping (DEM) to help a city manage stormwater issues. They continually had a stormwater basin overflowing, and the water pooling on the roads (i.e. not reaching the basin). Through 3D mapping we were able to demonstrate where flooding will occur, helped them determine any changes in their network required to drain the land better and size their basin for them (or suggest alternatives to transport the stormwater).

It could however also be used to benefit general stormwater infrastructure across a city (in Australia many cities are retro-fitting their urban areas with WSUD/bioretention gardens which replace traditional pits). The 3D mapping helps pick the location and flows for these.

Another project I was involved in required viewsheds and building shadows to be determined (this was in relation to tourism, property rights etc.) Also that same city used the 3D mapping to determine a height restriction on buildings within the CBD, and also to determine height based on the predominant wind direction (as poor planning in the past created a wind tunnel through the main street).